Coral alga may hold key to malaria prevention

A brown alga discovered in Sydney harbour by Sydney University scientists could provide the key to treating diseases that disable and kill millions each year.

{IMAGE}"Robert Moore, who was at the time doing a PhD in my lab, isolated an alga from a coral in Sydney harbour," said Associate Professor Dee Carter, Head of Microbiology in the Faculty of Medicine.

"On the surface it looks like any one of the numerous small algae we commonly refer to as plankton. But molecular analyses show it is actually related to a more sinister group of parasitic organisms that include Cryptosporidium, Toxoplasma and Plasmodium, the agent of malaria."

Scientist have known for some time that these parasites are related to algae as they contain a tiny relict of what was once a chloroplast - the subcellular organelle present in plants and algae that photosynthesizes to produce carbohydrates from sunlight and water.

The chloroplast found in these parasites indicates they are related to a group of single-celled algae known as dinoflagellates, often found in coral cells in tropical waters such as the Great Barrier Reef.

"Theoretically, knowing how dinoflagellates lost their ability to photosynthesize and become parasites could help us understand how malaria and other parasites evolved, but the problem is the gulf between the two types of organisms is huge," said A/Prof Carter.

"But now it seems the brown alga we've discovered - which is photosynthetic like dinoflagellates but is much more closely related to the parasites - is the 'missing link' in parasite evolution.

"Not only will this alga help us understand the transition to parasitism, we hope it can help us find and test new drugs against malaria and the other parasites, which remain among the most difficult diseases to treat."

http://www.usyd.edu.au